title: The roles of three forms of human thyroid hormone receptor in gene regulation.
abstract: We have expressed three forms of human thyroid hormone receptor (hTR alpha 1, alpha 2, and beta) in cultured cells by transient transfection. hTR alpha 1 and beta transfected cells showed increased triiodothyronine (T3) binding capacity, but hTR alpha 2 transfected cells did not. When hTR alpha 1 or beta was cotransfected with pUrGH(S), in which a portion of the rat GH 5' flanking region (-236/-147) was ligated into the CAT reporter plasmid (pUTKAT1), T3 increased CAT gene expression. When hTR alpha 2 was cotransfected with pUrGH(S), T3 did not alter CAT gene expression. When hTR alpha 1 or beta was cotransfected with pUrGH(O), in which a synthetic oligonucleotide representing the TRE from the rat GH 5' flanking region (-189/-160) was substituted for the natural enhancer in pUTKAT1, T3 increased CAT gene expression. When hTR alpha 1 and beta were cotransfected with pUrGH(O), induction by T3 was increased. When hTR alpha 2 was cotransfected with hTR alpha 1 or beta, induction by T3 was decreased. These results indicate that hTR alpha 1 and beta function as native TR, that hTR alpha 1 and beta can recognize the same TRE, that hTR alpha 1 and beta can function additively, and that hTR alpha 2 can inhibit the action of hTR alpha 1 and beta.
authors.affiliation: Department of Medicine, University of Chicago, IL 60637.
authors.forename: A
authors.initials: A
authors.lastname: Nakai
authors.forename: A
authors.initials: A
authors.lastname: Sakurai
authors.forename: E
authors.initials: E
authors.lastname: Macchia
authors.forename: V
authors.initials: V
authors.lastname: Fang
authors.forename: L J
authors.initials: LJ
authors.lastname: DeGroot
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D013006:Growth Hormone / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D012326:RNA Splicing; D051381:Rats; D011988:Receptors, Thyroid Hormone / Q000145:classification* / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014284:Triiodothyronine / Q000378:metabolism*
chemical_list: D011988:Receptors, Thyroid Hormone; D011993:Recombinant Fusion Proteins; D014284:Triiodothyronine; D013006:Growth Hormone